The aim of this project is to identify and characterize enzymes involved in the repair and replication of DNA in higher organisms. Currently we are 1) Examining the ability of a eukaryotic DNA ligase to seal single strand breaks in chromatin; 2) Characterizing a DNA kinase of unusual specificity also from eukaryotic sources; 3) Examining the number and characteristics of DNA ligases in rat liver; 4) Continuing to survey eukaryotic sources for a DNA gyrase-like activity.